1. Field of the Invention
The invention herein relates to a vacuum canister that is simple to manufacture and does not require the addition of extraneous structural devices on the cover. Vacuum can be produced through a direct manual operation.
2. Description of the Related Art
Utilizing containers to hold food stuff is a common practice in a majority of households. However, since the sealing capabilities of a container directly affects the storage period of the foodstuff enclosed within, therefore, a large number of so-called "vacuum canister" containers available on the market have been welcomed by consumers for utilization, wherein the operating principles are not based on having a perfect vacuum inside the container, but the drawing out of the air inside the container after the food has been placed within, thereby causing the production of an internal negative pressure by reducing the quantity of air inside the container to increase the storage period of the food. Furthermore, the negative pressure inside the container increases the sealing strength of the cover and the container of the aforesaid vacuum canister.
Referring to FIG. 1, a currently observed conventional vacuum canister generally has an empty container section (1) and a cover (2), of which there is a curved hook-shaped hinge (11) on one side of the container section (1) and a latch mount (12) on the opposite side. The cover (2) rests against the tabs (21) of the hinge (11) as well as the hinge (11) itself, and the cover, furthermore, is latched onto the catch plate (22) of the latch mount (12) such that the cover (2) and container section (1) are in an encapsulated state. The upper extent of the cover (2) has a recess hole (23). There is an annular channel (24), along the inner circumference of the recess hole (23), and a straight channel (25) at the center of the recess hole (23). Furthermore, there is an air hole (26) near the straight channel (25) at the lower extent of the recess hole (23).
A gasket (3) constructed of a flexible material has a circular section (31) that corresponds to the annular channel (24) in the cover (2), and a rib section (32) that can be inserted into the straight channel (25) in the cover (2). Furthermore, the rib section (32) has a membrane piece (33) that covers the air hole (26) on the cover (2).
A suction device (4) includes an end having a lip (41) protruding inward into the empty area within and another end that is a pipe opening (42) of a sleeve pipe (43); a handle (44) formed into one end of the sleeve pipe (43) and piston rod (46) of a piston (45) at the other end; a slot port (47) formed onto the aforesaid piston rod (46) and the form of the piston (45) consists of an interval (451) the lower extent and front which separates a front retaining edge (452) and a rear retaining edge (453). Furthermore, there is a flexible O-ring (454) in between the front retaining edge (452) and the rear retaining edge (453), and the outer diameter of the O-ring (454) tightly, accommodates the inner diameter of the sleeve pipe (43). The diameter of the O-ring (454) does not fully occupy the entire space of the interval (451), which thereby enables the O-ring (454) to be movable in between the front retaining edge (452) and the rear retaining edge (453). A minor interval remains because the outer diameters of both the front retaining edge (452) and the rear retaining edge (453) are smaller than the inner diameter of the sleeve pipe (43). Furthermore, there is a vent hole (455) in the area where the piston rod (46) and slot port (47) converge with the rear retaining edge (453).
When a conventional vacuum canister is utilized, as indicated in FIG. 2 the cover (2) is placed onto the container section (1). When the catch plate (22) is locked to the latch mount (12) for sealing, the gasket (3) is inserted into the recess hole (23), whereupon the circular section (31) is correspondingly inserted into the annular channel (24) of the cover (2) and the rib section (32) is correspondingly inserted into the straight channel (25) of the cover (2), at which time the membrane piece (33) on the rib section (32) enshrouds the air hole (26) on the cover (2). The pipe opening (42) of the sleeve pipe (43) extending from the suction device (4) is flush against the gasket (3) seated in the recess hole (23) in the cover (2). Then, the handle (44) is reciprocated. When the handle (44) is pulled upwards, the air inside the container section (1) is drawn upward by the action of the flexible membrane piece (33) through the air hole (26) in the recess hole (23) of the cover (2) and enters the sleeve pipe (43), at which time the O-ring (454) is moved towards the front retaining edge (452) and lodged within the interval between the front retaining edge (452) and the sleeve pipe (43). Therefore, the air drawn out of the container section (1) resides in the space between the piston (45) and the gasket (3) of the sleeve pipe (43). When the handle (44) is pushed downwards, as indicated in FIG. 3, the O-ring (454) is displaced towards the rear retaining edge (453) and, after separating from the former sealed disposition, leaves an interval between the rear retaining edge (453) and the sleeve pipe (43) without, however, unplugging the vent hole (455) in the rear retaining edge (453). Therefore, the aforesaid air drawn into and pressurized within the confines between the piston (45) and the gasket (3) of the sleeve pipe (43) at this time by the action of the membrane piece (33) can only pass through the interval between the front retaining edge (452) and the sleeve pipe (43) and the vent hole (455) in the rear retaining edge (453) for discharge of the overflow through the slot port (47). When the handle (44) is repeatedly pulled and pressed, such that air inside the container section (1) is only expelled and not inducted, a negative pressure is gradually produced within the container section (1), at which time, the movement of the suction device (4) is separated from the membrane piece (33) such that the cover (2) cannot be removed even when the catch plate (22) is unlatched.
Although the foregoing method of producing a vacuum inside a vacuum canister is widely utilized, the position and operation of the suction device (4) is not of ideal design. In use, (a) the vacuum canister cannot be employed if the user loses or is unable to find the suction device, and (b) when suctioning air, the suction device must be steadied with the other hand so the pipe opening of the sleeve pipe is held firmly against the gasket. Otherwise, there will be gaps between the pipe opening and the gasket that render suction impossible to achieve.